Most of the conventional microwave mixing circuits constructed of integrated circuits, employ two mixing diodes. However, because of requirement of two diodes, the cost of the conventional microwave mixing circuits is high, while it requires twice as much electric power for the local oscillation signal than in case of using a single diode.
As a countermeasure for the above-mentioned two-diode type microwave mixing circuits, several mixing circuits which require only a single diode are known. However, these known single-diode type microwave mixing circuits are not practical inasmuch as the amount of loss of the input high frequency is great and/or the amount of undesirable radiation of the local oscillation frequency is great.